The Bones: our Blood's *Calcium bank*

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The Bones: our Blood's *Calcium Bank*

JoAnn Guest

Jan 12, 2007 16:56 PST

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Calcium. are you getting enough? Too much? The solution isn't as

easy as gulping milk by the gallon or popping

supplements by the handful. To call calcium the most hyped mineral

in history would be an

understatement.There are dozens of heavily advertised supplements on

the market. On grocery store shelves, everything from orange juice

to

bread is fortified with it.Packages of antacids, such as Tums and

Rolaids, brag about their calcium content. And no one hypes the

health

benefits of calcium more than the dairy industry.

 

All these products claim to help prevent osteoporosis, the

deterioration of bone mass from calcium loss which afflicts

10 million Americans with 1.5 million fractures annually. The

specter of spending our senior years stooped over like a question

mark, slowly, carefully and painfully crossing the street with the

aid of a cane or a walker afraid of sustaining a serious or even

fatal injury from a simple fall, is frightening indeed.

 

It would seem, therefore, that we should all eat as many calcium-

rich

foods as possible and take calcium supplements to guard against this

debilitating condition, right? Wrong!

At least, not without knowing what we are doing. Studies have

shown that those who ingest large quantities of calcium can also be

high risk for developing osteoporosis.

 

The reason for this is that the amount of calcium we ingest does not

necessarily translate into the amount of calcium we absorb.

 

At least as important as the amount of calcium in our diet is the

type

of calcium we eat, and what we eat with it. Certain cofactors in

proper

proportion are absolutely necessary for the

body to absorb calcium, while other substances inhibit the body's

ability to do so.The amounts of gastric hydrochloric acid and the

acidity (pH level) of our bodies is also of fundamental importance.

 

Even our hormonal balance plays a key role in calcium metabolism.

Without taking all these factors into account, blithely loading up

on

calcium can actually result in a net *deficiency* of the mineral.

 

The bones: our blood's *calcium bank.* Bone cells are the body's

savings

account of calcium. When blood levels of calcium rise above

normal,the

excess is stored in the bones.Conversely, when calcium levels in the

bloodstream dip, the body turns to its bone bank to balance the

deficit.

 

 

Our serum calcium level is affected by many factors, many of which

are not directly related to the amount of calcium in our diets.

 

For example, stress can reduce free calcium by disrupting hormone

balance.Stress stimulates the production of the hormone cortisol,

which in turn increases levels of the steroid hormone aldosterone, a

key regulator of mineral balance in the body.

Chronic stress can reduce blood calcium levels, requiring the body

to

continually make withdrawals from the bone bank.

 

 

There is no question that we need an adequate dietary intake of

calcium. But how much is adequate? What are the best sources? And

what factors are necessary to absorb and utilize this calcium and to

maintain proper levels of calcium in both our bones and our

bloodstreams?

 

People equate calcium with dairy, and dairy products contribute 75%

of the calcium in American diets. Milk is a $19 billion industry in

the United States, and the Dairy Council spends hundreds of millions

of dollars in advertising and marketing every year. The Got Milk ad

campaign is among the most successful in advertising history.

However, scientists long have challenged the assumption that dairy

consumption equals strong bones. Now, thanks to new studies, their

argument is gaining momentum.

 

It's easy to understand why the dairy industry touts milk as the

perfect calcium conveyor.An eight-ounce glass packs 300 mg of

calcium along with significant amounts of vitamins A and D,

magnesium

and phosphorus, all cofactors for bone health.

Cheese and yogurt are similarly endowed. But not everyone swallows

the

idea that a diet chock-full of dairy is the best way to bank

calcium.

 

The dairy industry's armor was badly pierced five years ago by a

Harvard Nurses' Health study published in the American Journal of

Public Health. Researchers examined the diets of 77,761 women during

a 12-year period.

What they found was that drinking milk did not protect the

participants

against bone fracture. In fact, those who drank the most milk (three

or

more glasses a day) had more fractures

than those who barely touched the stuff (less than one glass per

week).

I'm not surprised that people who consume a lot of dairy don't

necessarily have better bones, says Diane Feskanich, lead author of

the

study and an epidemiologist at Brigham and Women's Hospital in

Boston.

 

Feskanich is still monitoring the nurses to see how they're

faring, and she hopes to publish more data sometime this year. We

updated the analysis and found the same results: We don't see fewer

hip fractures with higher milk consumption, she says. There is

definitely a link between Dairy consumption and osteoporosis.

What the Nurses' Health study showed is that, as a preventative

strategy against osteoporosis, eating dairy products is no better

than a placebo, says Neal Barnard, M.D., president of the Physicians

Committee for Responsible Medicine, a nonprofit organization that

opposes milk consumption.

 

The dairy industry is built on convincing people that it works.

 

A more recent strike against the dairy industry came in the form of

a

scientific review published in the American Journal of Clinical

Nutrition. Researchers at the University of Alabama gathered all of

the

credible clinical evidence they could find on bone health and

dairy-rich diets. After an exhaustive review of nearly five dozen

studies, they concluded that there is no solid body of evidence to

support eating dairy foods.

 

If dairy foods are so loaded with calcium, why are they not

protective of bones? One reason is dairy products' relatively high

sodium and protein content.

The body utilizes calcium to metabolize both protein and salt.

 

Approximately 1 mg of calcium is needed to process 1 g of protein,

and

Americans routinely eat 65 to 100 g or more of protein each day.

 

The authors of the study found that dairy foods, such as cottage

cheese

and processed cheeses, are so high in protein and sodium, which

actually

acidifies the blood, that the combination could actually negate the

food's calcium benefits. This discovery doesn't surprise Loren

Cordain,

Ph.D., an evolutionary biologist at Colorado State University in

Fort

Collins. [see Cordain's story, A Diet Solution Based on Evolution,

March

2002.]

Cordain is one of a growing number of theorists who believe that the

crux of Americans' high rate of osteoporosis is not a lack of

calcium

but our Western diet:

heavy on 'acid-inducing' proteins and light on 'alkaline-enhancing'

fruits and vegetables.

 

What we're seeing is a " calcium imbalance " , says Cordain. It's not

about

how much comes in, it's about how much is *going out*.

 

Americans have the highest rates of osteoporosis-related fractures

in

the world, yet we eat more dairy products than almost any other

country.

The data sticks out like a sore thumb.

 

Indeed, the facts are confounding. People in North America and

northern European nations consume two to three times as much calcium

as their Asian counterparts, yet break two to three times as many

bones.

 

The United States has one of the world's highest recommended daily

allowances for calcium, and it keeps creeping higher.

According to the National Academy of Sciences, which sets the RDA,

daily

calcium recommendations start at 1,300 mg for adolescents ages 9 to

18,

then lower to 1,000 mg for adults ages 19 to 50, and, finally, rise

again to 1,200 mg for people 51 and older. Reaching the RDA for

calcium

is virtually impossible unless you're

eating tons of dairy products, which is precisely the point, says

Cordain.

 

Cordain likes to refer back to the diets of hunter-gatherers for

dietary guidance. He points out that milk is a recent phenomena and

that if what dairy advocates say is true, then everyone living

before

the " age of milk " should have had osteoporosis. We don't find that

at

all, he says. What we do find are robust,

fracture-resistant bones.

Holistic nutritionists also point out the unnatural aspect of what

was touted by the dairy industry as nature's most perfect food:

No other mammal drinks milk from its mother after it is weaned, and

no

other species drinks the milk of another species.

 

Feskanich is also skeptical of the RDA for calcium. Upping the

calcium requirements doesn't seem to be helping prevent hip

fractures in

America, she says. It's almost as though we keep raising it in hopes

that it will have some effect,but apparently it's not working.

 

So what does all this mean to someone who wants to eat a bone-

healthy

diet? The science may be complicated, but the dietary advice is not.

Eat

plenty of fruits and vegetables

 

If you find it hard to believe that eating green vegetables is a

superior way to get adequate calcium, consider the diet of dairy

cows. These animals maintain their own huge bone structures and

produce calcium-rich milk from a diet of grass.

 

While it's true that, cup for cup some vegetables have less calcium

than milk, the body is able to absorb more of the mineral when it

comes

from a veggie source, explains Barnard, because it doesn't come

packaged

with protein and refined salt.

 

In fact, the body absorbs more calcium from spinach, kale and

broccoli

than from milk.

A 1997 study published in the New England Journal of Medicine found

that as participants upped their fruit and vegetable intake from 3.6

to 9.5 servings a day, their 'calcium loss' declined 30%.

 

A minimum of five servings of fruits and vegetables a day is

important

for bone health because it creates a more " alkaline environment " ,

and

less calcium is lost in the urine, Weaver says.

 

Among the richest sources of plant-based calcium are dark, leafy

greens, such as brussels sprouts, spinach, mustard greens, broccoli,

turnip greens and kale.

 

Don't depend on fortified foods.

When deciding where your calcium should come from, fortified foods

belong at the bottom of your list. The vitamins and minerals added

to

'processed' foods are necessarily the cheapest available, and their

sources and forms are uncertain. Foods that are artificially pumped

full

of calcium shouldn't replace natural sources.

 

There are so many beneficial factors in food that haven't even been

identified; you really need to go to foods first, says dietician

Lola

O'Rourke, a spokesperson for the American Dietetic Association.

 

Watch your salt intake

A high-sodium diet 'drags' calcium from bones to 'aid' digestion.

 

Every day, the typical American eats 3 to 4 g of sodium, equaling a

daily calcium loss of up to 80 mg. By reducing your daily sodium

intake

by 1 g, you'll save 1% of your skeletal mass each year.

 

This is just one more reason to use natural sea salt containing at

least

2% trace minerals, and do your best to avoid sinfully salty snacks,

such

as potato chips, fritos and microwave popcorn. Give high-sodium,

processed foods, such as fast foods and frozen dinners the boot,

too.

 

Trim protein

 

Eating just one meat-free meal a day can reduce your protein intake

by 40 g, meaning that 40 mg of calcium will stay in your bones,

where it

belongs.Plant-based proteins have the added advantage of

containing fiber, an adequate supply of which is essential for

proper

'digestive functioning'.

 

Calcium is absorbed from the small intestine into the bloodstream,

which

leads us to believe that the health of the small intestine directly

affects the amount of calcium we 'absorb' from our food.

 

Shun Sodas

 

Last year, scientists at Harvard found that teens quaffing soft

drinks were three times more likely to break a bone than those who

didn't partake. The risk of injury jumped to five times more likely

for girl athletes.

 

Some researchers point to phosphoric acid as the culprit. Excessive

phosphorus is thought to hamper calcium absorption.

 

Vitamin D is Vital

 

Vitamin D must be present in sufficient quantity for your body to

absorb calcium from the intestines into the bloodstream. Be sure to

get outside and obtain adequate sunlight. Our bodies synthesize

vitamin

D through the action of ultraviolet radiation on 'sterols' (fat-like

substances) in the skin.

You can also add vitamin D-rich organic egg yolks, broiled fish and

fish

oils to your diet.

 

For adults, the recommended daily allowance for vitamin D is 400 to

600

IU. Many seniors, especially those who are housebound, suffer from a

vitamin D deficiency. The

National Osteoporosis Foundation recommends up to 800 IU per day for

the elderly.

 

Exercise

 

Bone density rises and falls according to the demands placed upon

it, so

physical activity has lifelong implications for skeletal health.

 

Adults who were physically active during childhood have better bone

density than those who were couch potatoes. A recent study by

scientists at Pennsylvania State University found that exercise

during the crucial bone-building years is the best predictor of a

woman's adult bone health.

Researchers tracked the diets and exercise habits of 81 girls from

age

12 to 18.

Those girls who saw the greatest bone gains as adults were those who

exercised the most during their teens, not those who consumed the

most

calcium.

 

So, boost your bone density by hitting the pavement or the gym.

Experts agree that 30 minutes of weight-bearing exercise, such as

walking or jogging, three times a week is all it takes to see

results. Strength training is also an excellent way to keep bones

strong. Either way, it is never too late to start.

 

In studies that examined physical activity among the elderly,

exercise

reduced the risk of bone-breaking falls by 25%.

 

Exercise gives your bones a reason to live, says Barnard.

 

Check your stomach acidity

Calcium cannot be digested without sufficient stomach acid. It is

estimated that by age 50, most Americans have lost 50% of their acid-

producing stomach cells to protein overload, parasites, poisonous

substances in food and other factors.

 

Under the best of circumstances, only about 30% of the calcium we

ingest is absorbed; without sufficient hydrochloric acid in our

stomachs, this figure can drop as low as 4%. This is also why

antacids,

which claim to be a calcium source, actually 'work against' calcium

absorption.

 

Ironically, people take these products because they suffer from

heartburn, which they attribute to excess stomach acid.

 

Yet, according to gastroenterologist William Stuppy, M.D., the vast

majority of his mature patients suffer from 'too little' stomach

acid,

which can produce the same " symptoms " as excess acid.

Dr. Stuppy warns especially against taking acid blockers such as

Pepcid

AC.

 

For patients with chronic digestive problems, stomach pH can be

easily measured during routine tests. One more way to help your

stomach

is to chew your food well. Food that is thoroughly masticated

generally

requires less stomach acid to digest.

 

Supplement only with professional advice

When it comes to obtaining calcium from food, the options are

plentiful. However, long-term calcium supplementation, particularly

without the

other factors necessary for bone health, is not likely to stave off

osteoporosis. And without the advice of a qualified

holistic nutritionist or naturopathic doctor, it is possible to do

more harm than good. The amount of bone-density increase you get

from

supplementation is dubious, says Feskanich.

 

One theory is that it works initially and then plateaus. And there's

the

issue of consuming too much. Regularly ingesting calcium in excess

of

2,000 mg a day may cause constipation, kidney stones or other

problems.

 

Michael Borkin, N.M.D., often puts his patients on a calcium

supplement or, more accurately, supplements. He recommends rotating

the

form of calcium, however, between calcium

citrate (one of the easiest forms to absorb), calcium ascorbate and

calcium gluconate. He also makes sure his patients supplement the

necessary cofactors in proper proportion, vitamin D, boron and

magnesium.

 

The relationship between calcium and magnesium is a good example of

the complexities of calcium supplementation. Magnesium has an

inverse

relationship with calcium.

Both 'compete' for the same receptor sites in cells, but a proper

balance of both is necessary for health.The ratio can vary

considerably

from patient to patient.

 

The body can't absorb more than 500 mg of calcium at a time,

so supplements are best taken in small doses throughout the day.

 

Contaminants, such as aluminum and lead, are also a concern with

some

calcium supplements (such as Tums).

To find out if a supplement has aluminum, check the list of

ingredients

on the label. (Tums Contains Aluminum)

Avoid supplements made with bone meal, dolomite or oyster shells, as

they often contain lead.

 

Remember, ingesting more calcium is not necessarily the key to

preventing osteoporosis. But getting the right forms of calcium may

be

just what your body needs.

 

 

Men and calcium

A cautionary note

 

Calcium is usually talked about in connection with women and

osteoporosis (80% of osteoporosis sufferers are women), but more

than a

dozen studies show a link between a high-calcium diet and prostate

cancer. In one of the largest, scientists at the Harvard School of

Public Health studied the diets of 20,885 male physicians to tease

out the relationship between dairy products and prostate cancer

risk.

 

Their results, published in the October 2001 issue of the American

Journal of Clinical Nutrition, found that men who consumed more than

600 mg of calcium per day had a 32% increased risk of prostate

cancer

compared with those who took in less than 150 mg per day.

The authors concluded high calcium intake, mainly from dairy

products,

may increase prostate cancer risk

by 'lowering concentrations' of 1,25-dihydroxyvitamin D3, a hormone

thought to protect against prostate cancer.

For each additional 500 mg of calcium from dairy products per

day, researchers saw a 16% jump in the men's prostate cancer risk.

 

There's a general message that the more calcium the better, says

June

Chan, the study's lead author. That's not necessarily the case,

especially for men.

 

Even more surprising were results from a 1998 study that traced the

health of 50,000 men. The researchers found that those men who were

avid

calcium consumers

(more than 2,000 mg per day) had a nearly

fourfold increase in the incidence of prostate cancer over their

calcium-shirking counterparts (500 mg or less a day).

 

Should men swear off calcium-rich foods? Chan says no. She suggests

that men are safe to stay within their RDA of 1,200 mg and can avoid

going overboard by taking a hard look at how much calcium they take

in daily,adding up the calcium they consume from dairy products,

fortified foods and multivitamins.

 

Don't forget to tally the calcium in antacids; Chan suspects that an

overdependence on the stomach soothers may be to blame for men's

megadoses.

Other experts aren't so willing to rely on the RDA. Chan's advice is

flat out wrong, says Neal Barnard, M.D. He feels that medical

researchers, like Chan, are simply afraid to take a stand against

the

dairy industry.I understand that people hate to make a

recommendation

against a product that we've known and loved, but enough is enough,

says

Barnard.

We can't cut the risk of prostate cancer to zero, but there are

things

that help. I think men would be well-advised not to drink milk.

 

 

Why We Need Calcium

 

There's no doubt that calcium is crucial to good health. It is the

most abundant mineral in our bodies, making up 1.5% to 2% of our

weight.

Ninety-nine percent of this is stored in our bones and teeth;

our bones consist of about 70% calcium salts by weight. Calcium

makes

our bones strong and rigid by forming part of the substance that

cements

together the walls of adjacent cells.

 

But calcium does more than maintain our skeletal structure. It is

essential for the normal functioning of all body cells, acting as a

mediator for many vital cell functions.

 

While our bones contain 99% of our calcium, the remaining 1% of free

calcium circulating in our soft tissues, bloodstream and

extracellular

fluid also performs some

crucial functions.

 

For example, without calcium, blood will not clot. Calcium also

regulates muscles' contractility

and the beating of our heart. It regulates neurotransmitters at

synaptic junctions, where nerve impulses are passed from one neuron

to another, and calcium disregulation can cause mental and emotional

problems.

 

The body carefully regulates these calcium levels, keeping them

within the range of 50 to 65 mg per liter of extracellular fluid.

More or less than this can quickly lead to serious and even life-

threatening conditions.

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JoAnn Guest

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